In the production of garments and other textile products in a high volume industrial assembly process in which the work pieces are sewn together, it is important that the sewing equipment provided to the worker be fast and efficient in its operation, and also that the equipment be capable of being quickly and easily loaded with the work pieces by the worker. Further, it is highly desirable that once the work pieces have been properly loaded in position, and the equipment placed in operation, that the equipment accurately form the desired work piece without errors so that the production of "seconds" is avoided.
In the production of garments and other items which are to be purchased as high quality goods, therefore, it is important that the hems and seams connecting the adjacent work pieces be accurately formed, as by the stitching for a hem extending through the edge portion at the raw edge of a folded hem, rather than allowing the stitching to wander off or away from the edge portion. In those instances where a line of stitching in a continuous hem overruns and merges with itself at the beginning and end of the line of the stitching, it is important that the end of the line of stitching and the beginning of the line of stitching be closely aligned with one another. If the beginning and end of the line of stitching are misaligned where they overlap, an undesirable visual appearance will be created and it is likely that the garment will be considered a "second" and refused by the potential purchaser.
For example, when a folded hem is formed at the waist line of a tubular knitted shirt the typical and desirable stitch formation comprises two lines of parallel stitches formed on the external surface of the garment, with connecting stitches on the rear surface holding the former raw edge portion of the hem in place. It is important, then, to make sure that the parallel stitches at the beginning and at the end of the run of stitches about the garment are aligned as they overlap to create a pleasing visual appearance.
The prior art automated work piece guide systems that form hems in the continuous edges of tubular garments, such as the waist hem of a knitted shirt, do not have the consistent ability to align the work pieces with the sewing machine so that overlapping stitches at the beginning and end of a stitch run are aligned. Also, the line, or lines, of stitching may not be aligned with the raw edge in the hem of the garment because the depth of the hem might vary along its length. These problems seem to be generated because the known prior art devices first guide the unfolded raw edge along the processing path until the edge portion is folded over onto the adjacent body portion to form the hem, and then guide the folded edge of the hem along the processing path to a downstream sewing machine.
A guide system of this general type is disclosed in U.S. Pat. No. 4,497,447. If the tension changes in the work piece during the operation of the equipment, or if the folder does not function perfectly, the depth of the folded edge portion of the hem may vary along the length of the hem causing the raw edge of the garment to wander out of alignment with the stitches as the garment advances through the sewing machine. Moreover, when the sewing of the hem in the work piece begins, the alignment of the work piece and the depth of the fold may not be as accurate at the beginning of the sewing cycle as it will be during the middle and end portions of the cycle, so that the line of stitches formed at the beginning of the stitching function may be displaced to one side or the other of the desired stitch track. In this situation, the beginning and ending stitches of an overlapping stitch run may be misaligned and form an undesirable appearance.
What is needed, therefore, but seemingly unavailable in the art is a guiding system for use with multiple ply seam textile work pieces which will repeatedly, accurately, and quickly guide the folded raw edge portion of a work piece toward a hem forming station, for example, to ensure that a uniform hem is sewn into the work piece, and which will ensure that the lines of stitching remain parallel to and aligned with one another along the raw edge of the work piece.